An idea for a low gain high input level preamp
A one transistor EF pre
+24vdc supply
Bias string 10K one end to 24 V other end to a node A one end of a 22K. the other end of the 22k to ground. A 100uf cap connected to the node A and other end to ground.
The EF stage a 2n4401 collector to 24V. Base to node B emitter to a 2.2K emitter R and the other end of the 22k to ground.
the secondary of an input transfromer one end to node A and the other to node B Maybe a transformer like the LL7905 setup as 1:5.6 or 1:11.2.
With something this simple the secondary of the transformer might need a resistor from node A to node B. The input R of the transistor will be about hfe( at about 8ma) X the emitter R so a resistor in parallel with the secondary might help with termination.
The unbalence output will be taken off the emitter of the transistor. Yes we want the emitter to sit at about 18V
feedback please.
A one transistor EF pre
+24vdc supply
Bias string 10K one end to 24 V other end to a node A one end of a 22K. the other end of the 22k to ground. A 100uf cap connected to the node A and other end to ground.
The EF stage a 2n4401 collector to 24V. Base to node B emitter to a 2.2K emitter R and the other end of the 22k to ground.
the secondary of an input transfromer one end to node A and the other to node B Maybe a transformer like the LL7905 setup as 1:5.6 or 1:11.2.
With something this simple the secondary of the transformer might need a resistor from node A to node B. The input R of the transistor will be about hfe( at about 8ma) X the emitter R so a resistor in parallel with the secondary might help with termination.
The unbalence output will be taken off the emitter of the transistor. Yes we want the emitter to sit at about 18V
feedback please.